1. Technical Field
The invention relates to manufacturing methods of an electronic board and a multilayer wiring board.
2. Related Art
Recently, down sizing of electronic components to be mounted on a circuit board (wiring board) has been advanced and thus a minute wiring board is required. As for a method of forming the above stated minute wiring structure, there is such a technique that a conductive pattern is embedded in an insulation film using a droplet discharging method (see JP-A-2005-327985 which is an example of related art).
Down sizing has also been advanced recently with regard to electronic devices such as a cellular telephone, which includes the above described circuit board. A cellular telephone has only a limited space for receiving electronic components provided on a circuit board (wiring board). Therefore, such a method is required that the electronic components can be packed in high density.
In view of the above described circumstances, such a wiring board is considered that chip parts are packed in high density by employing a process that the chip parts are secured onto a substrate to apply an insulation material around the chip parts using the droplet discharging method, followed by embedding the chip parts in the insulation film and forming wirings to be connected to the chip parts.
The above described conventional technique, however, has problems as follows.
An ink having an insulation property may flow over conductive parts provided on upper surfaces of electronic components when the insulation material is disposed around the electronic components by means of the droplet discharging method when the electronic components are embedded in the insulation film. The insulation film formed of the ink having the insulation property, the ink having been cured under the above stated condition, covers the conductive parts of the electronic components, such that there arises a problem that no conduction can be established between wirings formed on the insulation film and the electronic components, resulting in causing a poor connection therebetween.
If side surfaces of an IC chip has, for example, a water-repellant property against the ink having the insulation property, the ink having the insulation property would not closely fit the side surfaces of the chip, such that there may be a case a space is produced between an insulation layer and the side surfaces of the chip. In this case, if the conductive wirings to be connected to an IC pads are formed over an insulation film having been provided around the IC pads, there may be a possibility of disconnection of the conductive wirings, resulting in also causing a poor connection.